All photos courtesy of Autospray
Tree planting is at the root of the global response to climate change, helping offset pollution by sucking up carbon emissions, boosting natural biodiversity in the process.
The UK government pledged to plant 30,000ha of new woodland each year by 2025, as part of its commitment to reach net zero carbon by 2050. But it consistently fell short of this target and just 15,580ha of newly-created woodland was reported in 2024/25, according to Forest Research.
Sam Manning, project manager for south-west rainforests at conservation charity the Woodland Trust, says the biggest issues holding back progress are land availability, a lack of qualified officers in local councils needed to move schemes forward, and cash flow.
“For a lot of landowners, funding the schemes is a real problem, so if we can make them half, four, or eight times less expensive, it will inherently unlock a lot more woodland creation and save the taxpayer a massive amount of money,” says Manning.
Technological innovation can help boost productivity and cut costs and hopes are high that using autonomous drones to scatter seeds across large areas could revolutionise forest regrowth in the UK. Many potential woodland creation sites are either too steep, unsafe, or remote for traditional methods of planting or spreading seeds, making drones a promising solution.
A recent trial, funded by the government’s Department for Environment, Food & Rural Affairs (DEFRA), saw the Woodland Trust partner with the South West Rainforest Alliance and contractor AutoSpray Systems to distribute 75,000 native seeds by drone across the landscape of Bodmin in Cornwall.
An XAG drone, weighing 110kg and able to carry up to 58kg of seeds in its hopper, hovered a few metres above the ground dispersing seed onto sloping or hard-to-reach sites. These are normally inaccessible or unsafe for human tree planters or patches where soils are too thin to allow planting with spades.
The autonomous machine was able to seed 10ha of land in just eight hours, a scale of work not possible using conventional means.
Qualified surveyors were critical to the pilot, baselining the habitats to be seeded, mapping out locations for the drone to fly, and helping secure landscape permissions. Now the partners are moving ahead with a more ambitious second phase, having secured the first ever permission from regulator the Civil Aviation Authority (CAA) to fly drones beyond the visual line of sight (BVLOS).
“We want to make woodland creation and woodland restoration far more accessible in terms of how efficient, scalable and cheap it is, so we can meet challenges around nature recovery and particularly climate mitigation,” says Manning. “The Climate Change Panel targets are legally binding, so if we're going to meet them, we need new technology.”
An XAG agricultural drone, used for seeding
Moving equipment across terrain manually so that drones remain in visual line of sight
Limited resource
Rainforests are typically associated with tropical, humid countries, but milder climates in the mid-latitudes are also home to temperate rainforests characterised by cool temperatures, abundant moisture and rare ecosystems providing vital habitats for diverse wildlife.
Roughly three-quarters of Devon and Cornwall was once rainforest, but 90% of this has been lost, making these ancient woodlands, rich in biodiversity, among the most precious and threatened habitats in Britain.
According to the South West Rainforest Alliance, more than 1,000 species of native plants are found in surviving rainforest, including rare ferns and mosses, and at least 300 species of environmentally sensitive lichens, making their conservation a top priority.
The Bodim trial involved the development of a new seeding technique, which if fully implemented, the Alliance believes could triple the area of temperate rainforest in Devon and Cornwall from 8% to 25% of land area by 2050.
Andrew Sproson, co-founder of AutoSpray Systems compares his drones to mechanical birds that mimic natural rewilding processes from a bygone era when there were fewer built up areas and birds, squirrels and other animals would distribute seeds to expand forests naturally.
“Our drones are trying to replicate nature and give it a bit of a helping hand – we get hundreds of thousands of seeds down per hectare in minutes,” says Sproson.
The project partners ran experiments to develop and refine a custom seed mix incorporating pedunculate oak, alder, wild cherry, downy birch and hazel, all British trees native to rainforests.
These were loaded into a hopper on the underside of a drone fitted with a spinning corkscrew-like auger, which pushes the seed towards a fan that disperses the seeds at a steady rate.
“We spent months developing the concept of a seed mix, with the Woodland Trust giving their expert opinion. We had to figure out a way to make it commercially viable and do it as quickly as possible to a high standard,” says Sproson.
While a birch seed is light and equivalent in size to a grain of instant coffee, an acorn is much larger and heavier, making it harder to create a mix that could be applied evenly. The solution was to apply a clay-based coating to the smaller seeds to give them extra bulk and weight. Wood pellets and sawdust were mixed in to achieve the right consistency.
“Rural surveyors can play a pivotal role in evaluating where and how this technology creates best value” Ed Randall MRICS, Woodland Trust
Getting the seed mix right is crucial
Loading seed into the hopper
Expert input
Surveyors at the Woodland Trust were critical to pinpointing where precisely to fly the drone. Remote areas of improved grassland, upland moorland and an ex-mining site with extremely degraded soils dominated by bryophytes – small gorse and heather – were all targeted.
“How do I know that I'm going to hit a particular patch on a ravine with a 50% gradient, how am I going to get to that area accurately?” said Sproson, “That's where the survey data came in. The team supplied us with a shapefile [a geospatial vector data format used to define areas and boundaries], which the drone uses to navigate.”
In addition, surveyors baselined the most suitable habitats for reseeding and oversaw landscape permissions and applications for conversion to woodland. For example, the ex-mining site is in a National Character Area, within a sight line of a significant tourist area, requiring various Environmental Impact Assessments.
Ed Randall MRICS, land and property manager at the Woodland Trust, says: “This drone seeding trial demonstrates how rural surveyors can play a pivotal role in evaluating where and how this technology creates best value. By assessing soil conditions, topography, and species mix, surveyors are well placed to advise landowners on practical deployment, monitor establishment success, and integrate drone seeding into broader land management strategies.”
The reseeding process saw the drone fly autonomously, its path guided by data in an app which set the height and speed, area of operation and application rate based on the project research.
As the team eagerly awaits results on seed germination and coverage rates – expected in 2027/28 – other lessons are already being learned.
According to the Woodland Trust, the standard AXG drones deployed struggled with larger seeds and needed frequent clearing, so modifications will be required for future trials. Although the process was considerably cheaper than conventional planting, costing around £2,000 per hectare compared to £3–4,000, the seed market was found to be inadequate to meet demand at this scale. Obtaining volumes at even the lowest densities, of 2,000 seeds per hectare, was a challenge.
The trial was a logistical headache, Sproson notes, requiring physical effort to shift equipment across difficult terrain to get close enough to maintain visual line of sight with the areas of drone operation, as per regulatory requirements.
“Our drones are trying to replicate nature and give it a bit of a helping hand” Andrew Sproson, AutoSpray Systems
Once the drone is airborne over the target location, a fan helps disperse the seeds at a steady rate
Sky’s the limit
A follow-on trial – the ‘Beyond Restoration’ project involving AutoSpray, National Trust, the Woodland Trust, and North Pennines National Landscape is funded by Innovate UK’s Future Flight Programme. It aims to address this issue, by allowing drones to fly BVLOS for the first time.
The Woodland Trust aims to establish five BVLOS-approved sites to seed new native trees across over 40 hectares, including sites in the North, the Midlands, an expansion of the Bodmin trial sites and possibly also Dartmoor.
Other enhancements will include higher seed densities, ranging from 20,000 to 200,000 per hectare, additional species, such as hawthorn and rowan, improved ground preparation and new drone technologies, potentially including 3D printing to create bespoke parts.
According to Manning, the aim is to focus on ex-mining sites where there is minimal risk to humans from drones and where vegetative competition is reduced, meaning a higher percentage chance of seed germination. Results will be carefully monitored to ensure there are no negative impacts on wildlife or people.
Drone-based afforestation is non-existent in Europe but more commonplace in countries like the USA, Africa and China, mainly due to the vast distances involved.
“Looking at how successful it is abroad, and how cheap it has made reforestation, there's no reason why we couldn't see the same thing happen here,” says Manning, “Lots of contractors are already rushing to become early adopters and do this kind of work, they view it as an attractive potential new market.”
